I shake uncontrollably and I feel really silly and try to stop e_e Like right before I have to make a big speech or something, or when people confront me with something I don't want to talk about... or when I'm at the doctors, or just scary situations. I hate it. xD I just start shaking. Luckily that doesn't happen too often.

I bite my fingernails on a normal basis though, not because I'm nervous or anything ^.^